Groundwater sampling in the field of environmental pollutant characterization traditionally consists of removing a specified volume of water from a groundwater well (“purging”), monitoring physical and chemical parameters of the “purged” water for indication that “fresh” ground water has been drawn into the groundwater well from the surrounding formation. This is accomplished by pumping or bailing water from the well and measuring physical and chemical parameters with instruments at the ground surface (e.g. thermometer, pH meter, electrical conductivity meter).
After purging, water samples are commonly taken from the well using a bailer and poured into containers for storage/transport to an analytical laboratory for testing. The storage and transport containers are made out of various materials such as glass or polyethylene and in sizes ranging typically from 40 milliliters to 1 liter. The size and type of container are selected based on requirements of the analysis to be performed. Volatile organic compounds such as benzene or trichloroethene are stored and transported in specifically-sized 40 milliliter volatile organic analysis (VOA vials). VOA vials are sized so that they can be placed in automated laboratory analytical equipment that use that size vial. Other analytes (e.g. metals, pesticides) are stored in different size and material containers to avoid adsorbance to the bottle material and to provide sufficient volume for analysis.
Improvements to purging/sampling techniques have been introduced by others to limit the amount, or eliminate outright, the water that needs to be “purged” from a groundwater well. These techniques include low-flow purging and no-purge “passive” methods. These methods may reduce or eliminate the need to bail water from the well after purging, but sample bottles are filled at the ground surface by pouring in the open air.
The following briefly describe traditional and newer sampling methods and equipment, and some of the disadvantages of each.
The Bailer
Fluid sampling equipment traditionally consists of some type of bailer, scoop, or pail that may or may not have a bottom filling device and some type of closure, such as a check ball or valve to contain the fluid. The sampling equipment is used to transport the fluid from the remote sampling location (inside a well or tank) to the point where the person conducting the sampling can transfer the fluid into appropriate containers for transport and/or testing. In the environmental industry, sampling from groundwater monitoring wells commonly consists of lowering a bottom-filling bailer into the well water, then raising the bailer, causing a check ball to seat—retaining the water within the bailer tube. Once the bailer is brought to the surface, the water sample is poured into containers for shipment to an analytical laboratory for testing. This method of groundwater sample collection has several disadvantages. These include:                a) The sampled water must be poured into separate containers after the bailer is brought from the remote location to the sampling personnel.        b) Volatile chemicals, which are commonly contaminants of concern in the groundwater to be tested, tend to off-gas when exposed to air during movement of the open sampling device and pouring into separate containers.        c) Lowering and raising a sampling device into a groundwater well, or other fluid containing vessel, can agitate solids into suspension (induce turbidity) within the liquid to be sampled.        d) Agitated solids, once enclosed in a bailer, are prevented from falling out of a bailer-type sampling device because of a solid bottom or check ball.        e) Lowering a bailer through a liquid allows only limited flow through of fresh liquid, limiting the utility of sampling stratified liquids.The Diffusion Bag Sampler        
The diffusion bag sampler (U.S. Pat. Nos. 5,804,743; 6,196,074) is a no-purge, passive, sample collection device that removes some disadvantages of the bailer, but has additional disadvantages. This device consists generally of a closed polyethylene (or other material) bag with or without structural support, filled with water. In its typical use, the filled bag is lowered into a groundwater well, left for a period of time (typically two days to two weeks) while volatile organic contaminants diffuse from the surrounding water through the bag into the water contained inside the bag. The sampler is raised to the surface, and water sample is poured into separate containers for transport to an analytical laboratory. This method of groundwater sample collection has several disadvantages. These include:                a) Like the bailer, water samples collected with the diffusion bag sampler must be poured into separate containers for transport to an analytical laboratory.        b) Diffusion bag samplers are limited to chemicals that will diffuse through a polyethylene (or other material) membrane. Many chemicals of concern for groundwater contamination will not diffuse through polyethylene, including for example, dissolved metals; or diffuse poorly, such as methyl tertiary butyl ether (MTBE), acetone, and methyl ethyl ketone (MEK).        c) Diffusion bag samplers must be left in place for as long as two weeks for the diffusion process to reach full equilibrium between the inside and outside of the bag.        d) Different chemicals diffuse through the membrane at different rates, meaning that if water chemistry changes during the time the diffusion bag is deployed, it is uncertain all chemical are indeed in equilibrium inside and outside the diffusion bag.The Niskin Bottle        
The fluid sampling equipment collectively described here as the “Niskin Bottle” consists generally of an open tube with a closure device at either end that is triggered (closed) remotely (U.S. Pat. Nos. 4,037,477; 4,091,676). The sampler is ordinarily used for sea- or lake-water sampling at depth. The closure devices consist of ball valves or other closure means attached by a rubber band through the openings of the open tube. The sampler is open during deployment or opened at the designated sample point. Fluid enters the bottle at either end and is trapped within the sampler when the closures are triggered remotely. The sampler is raised to the surface, and water sample is poured into separate containers for transport to an analytical laboratory. This method of water sample collection has several disadvantages. These Include:                a) Like the bailer, water samples collected with the Niskin Bottle sampler must be poured into separate containers for transport to an analytical laboratory.        b) The Niskin Bottle in its commonly-used embodiment is large and bulky. Its size precludes it from being used in typical ground water monitoring wells used in the environmental industry (2 to 4 inch inside diameter is most common).        c) The trigger mechanism and outer appurtenances of the Niskin Bottle also do not lend themselves to insertion in groundwater monitoring wells even if they were small enough because projections from the bottle are subject to binding and catching on casing joints within monitoring wells. This could cause premature triggering of the closure mechanism or the sampler becoming stuck within the well, an obvious disadvantage for collecting a water sample from a well.The Kabis Sampler        
The Kabis Sampler (U.S. Pat. Nos. 5,454,275; 5,686,673) solves some of the problems of the bailer by utilizing a standard volatile organic analysis vial (a 40 milliliter vial) to collect samples in a monitoring well—avoiding the pouring of sample into separate sample containers. However, this method of water sample collection has several disadvantages. These Include:                a) During deployment and submergence, the Kabis sampler degasses by bubbling air through vents in the sampler. This may result in off-gassing of volatile organic compounds within the well.        b) The sample vial remains open while the sampler is brought from its remote location (in a well, for example) and until the user screws on the vial cap. This results in exposure of the water sample to the atmosphere, possibly allowing VOC off-gassing.        c) The sample vial is open only at one end. Like the bailer, solid material can become entrapped in the sample vial.        d) Deployment of the sampler also tends to agitate water in the well and can increase turbidity in collected samples.The Kemmerer Sampler        
The Kemmerer sampler (see U.S. Pat. No. 5,487,314) is similar to the Niskin Bottle in that it is comprised generally of a hollow tube with end closures that are triggered and close mechanically. A fluid sample is contained within the apparatus for retrieval from a remote source. Like the other examples described above, this sampling device has several disadvantages. These include:                a) Like the bailer, water samples collected with the Kemmerer sampler are typically poured into separate containers for transport to an analytical laboratory.        b) The Kemmerer sampler in its commonly-used embodiment is large and bulky. Its size precludes it from being used in typical ground water monitoring wells used in the environmental industry (2 to 4 inch inside diameter is typical).        c) The trigger mechanism and outer appurtenances of the Kemmerer sampler also do not lend themselves to insertion in groundwater monitoring wells even if they were small enough because projections from the bottle are subject to binding and catching on casing joints within monitoring wells. This can cause premature triggering of the closure mechanism or the sampler becoming stuck within the well, an obvious disadvantage for collecting a water sample from a well.Other Tubular-Body Fluid Samplers        
Several other examples of tubular-body samplers with various closures exist in the prior art. These other samplers are exemplified by patents such as U.S. Pat. Nos. 5,341,693; 5,094,113; 4,590,810; 4,078,433; and 5,410,919. Various closure mechanisms typically differentiate the devices.
Each of the prior art devices described above, except the Kabis sampler, require pouring of collected fluid into separate sample containers for transport and/or chemical testing at an analytical laboratory. The prior art described above includes exposure of the collected sample to the atmosphere during pouring of fluid into separate sampling containers or closure of the sample containers at the surface. This is a clear disadvantage, especially for volatile chemicals that may escape the sample and bias results.
It is an objective of the present invention to provide a means to provide a sample container that permits fluid samples to flow freely through the container to avoid well purging for groundwater sample collection and to minimize induced turbidity and solids in samples. It is a further objective to provide a sample container that may be remotely closed securely within the fluid sample so as to collect self-contain samples in a manner that precludes exposure of the sample to the atmosphere from the time of sample collection, throughout storage and transport, to the laboratory testing apparatus.
It is a still further objective of the invention to provide a fluid sampling device for remotely deploying and securing one or more sample containers. It is yet a further objective to provide securing caps for the sample container to prevent leakage and contamination during transport and storage of the sample containers so as to reliably test virtually any chemical or physical parameter in the fluid. It is still a further objective to provide a method of drawing a sample from the sample container without disturbing the container seals. It is another objective of the invention to provide a means for pressurizing the contents of the sample container without disturbing the container seals. It is yet another objective to provide a combination sample container and fluid sampling device that can fit smoothly into narrow pipes and passageways. Finally, it is an objective of the invention to provide a durable and inexpensive fluid sampling system that is adaptable to a variety of fluid sampling environments.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.